Molecular basis of a progressive juvenile-onset hereditary cataract
Molecular basis of a progressive juvenile-onset hereditary cataract
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DOI：
10.1073/pnas.040554397
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发表时间：
2000-02-29
影响因子：
11.1
通讯作者：
Benedek, GB
中科院分区：
文献类型：
--
作者：
Pande, A;Pande, J;Benedek, GB
在最近的一篇论文中，已经报道了患有进行性青少年发病遗传性白内障的患者在人γ D晶体蛋白基因中具有点突变（Stephan，D.一、Gillanders，E.，Vanderveen，D.，Freas-Lutz，D.，维斯托，Escherevanis，A. D.生罗宾斯角，澳-地M.，VanAuken，A.，Quesenberry，M.一、Bailey-Wilson，J.，等人（1999）Proc.Natl. Acad. Sci. USA 96，1008-1012）。该突变导致天然蛋白质中的Arg-14被Cys残基取代。目前还不清楚这种突变如何导致白内障。我们已经表达了重组野生型人γ D晶体蛋白（HGD）和其Arg-14 Cys突变体（R14 C）在大肠杆菌中，并表明R14 C形成二硫键连接的寡聚体，这显着提高相分离温度的蛋白质溶液。最终，R14 C沉淀。相反，HGD缓慢地仅形成二硫键连接的二聚体而不形成寡聚体。这些数据有力地表明，所观察到的白内障是由硫醇介导的R14 C聚集引发的。HGD和R14 C的聚集概况与我们的同源性建模研究一致，其揭示R14 C含有两个暴露的半胱氨酸残基，而HGD仅具有一个。我们的CD，荧光和差示扫描量热法研究表明，HGD和R14 C具有几乎相同的二级和三级结构和稳定性。因此，与目前的观点相反，蛋白质的解折叠或不稳定对于白内障发生不是必需的。
In a recent paper, patients with a progressive juvenile-onset hereditary cataract have been reported to have a point mutation in the human gamma D crystallin gene (Stephan, D. A., Gillanders, E., Vanderveen, D., Freas-Lutz, D., Wistow, C., Baxevanis, A. D., Robbins, C. M., VanAuken, A., Quesenberry, M. I., Bailey-Wilson, J., ef al. (1999) Proc. Natl. Acad. Sci. USA 96, 1008-1012). This mutation results in the substitution of Arg-14 in the native protein by a Cys residue. It is not understood how this mutation leads to cataract. We have expressed recombinant wild-type human gamma D crystallin (HGD) and its Arg-14 to Cys mutant (R14C) in Escherichia coli and show that R14C forms disulfide-linked oligomers, which markedly raise the phase separation temperature of the protein solution. Eventually, R14C precipitates. In contrast, HGD slowly forms only disulfide-linked dimers and no oligomers. These data strongly suggest that the observed cataract is triggered by the thiol-mediated aggregation of R14C. The aggregation profiles of HGD and R14C are consistent with our homology modeling studies that reveal that R14C contains two exposed cysteine residues, whereas HGD has only one. Our CD, fluorescence, and differential scanning calorimetric studies show that HGD and R14C have nearly identical secondary and tertiary structures and stabilities. Thus, contrary to current views, unfolding or destabilization of the protein is not necessary for cataractogenesis.